Pulse Oximeter with Accelerometer for Activity-Based Power Management
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Solution Overview
Problem
Current pulse oximeters have high power requirements, making them unsuitable for integration into small, patient-worn electronic patches, and their readings can be misleading due to lack of activity context, which affects the accuracy of blood oxygen and heart rate measurements.
Innovation Solution
A pulse oximeter system integrated with an accelerometer, where a processor controls the operation of the pulse oximeter based on accelerometer data to determine patient activity states, turning it on only during rest periods to increase measurement accuracy and reduce power consumption, using a low power source like a coin cell battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the pulse oximeter operates continuously to provide constant monitoring, then measurement coverage is improved, but power consumption increases
Solution Approach 1:
The system transitions from continuous operation to periodic operation by using the accelerometer to detect activity states and controlling the pulse oximeter to operate only during rest periods. This periodic activation based on detected conditions reduces power consumption while maintaining clinically relevant monitoring coverage.
Solution Approach 2:
The accelerometer continuously monitors patient movement and automatically controls the pulse oximeter operation based on detected activity levels. The system serves itself by using its own sensor data to intelligently manage power consumption without external intervention.
2Loss of information
If the pulse oximeter operates during all activity states, then measurement completeness is improved, but measurement accuracy deteriorates due to motion artifacts
Solution Approach 1:
The system extracts and removes measurements taken during high-activity states from the monitoring data set. By using accelerometer data to identify and exclude motion-contaminated readings, the system maintains measurement completeness for analysis while eliminating accuracy-degrading data points.
Solution Approach 2:
The accelerometer provides continuous feedback about patient movement that is used to dynamically adjust pulse oximeter operation. This feedback loop ensures measurements are only taken when motion artifacts are minimized, maintaining both completeness and accuracy.
3Measurement precision
If a high precision current sink is used to control LEDs, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The system dynamically adjusts the operational requirements of the pulse oximeter based on activity detection. During rest periods when measurements are taken, the full precision of the current sink is utilized. During activity periods, the system reduces operational demands, allowing for more efficient circuit designs that balance precision with power consumption and complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of blood oxygen and heart rate measurements by correlating them with activity states, reduces power consumption, and allows for extended battery life in wearable devices, providing significant diagnostic capabilities in a single patch.
Implementation Method 1
an accelerometer disposed within a wrist module that is attached to the user's wrist
Implementation Method 2
light emitting diodes (LED's) which are driven with a voltage controlled source
Data Source
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AI summary
Systems, methods, and devices of the various embodiments provide a pulse oximeter capable of taking blood oxygen readings based on readings from an accelerometer. The various embodiments may provide an electronic patch including a pulse oximeter and accelerometer connected to a processor, wherein the processor is configured with processor executable instructions to control the operation of the pulse oximeter based at least in part on data received from the accelerometer. In various embodiments the electronic patch may further include a coin cell battery, or other low power source, that may power the pulse oximeter.